My PC would restart when I'd close the game. I'd get BSoD (Blue Screen of Death) for 0.5 secs and then it'd restart. I've fixed that by turning the ''Enable Multi-GPU'' option in NVidia Control Panel off. Since then it works like a charm. No crashes no freezes.

i dont know what power supply i got ,sorry for that,i will find it out soon though.i have installed a fresh copy of windows vista,let me try it agian.last time my computer also restarts when i quit the game,but it happen the first few time and then it changed to in-game restarting?funny huh?i got the latest ATI driver from the website.let me try it on vista then i let you people know